Jetting with Big Gun Exhaust on a CRF150R

[mlozier]

I have an 07 CRF 150R that has always had an idle problem.

I have installed a Big Gun full exhaust system and the Rekluse Pro clutch. We ride all year long at about 1000 to 2000 ft elevation in weather from 40 to 100 degrees.

What jetting specs can be recommended? Big Gun does not post any jetting specs for this bike.

[Joe Hunt]

I want to know the same thing

[gsa102]

Try a # 45 pilot jet first at that elevation.  IMO, The stock 40 is too lean until you get up to 2500+ feet.  I have always had idling issues with our 08, but it starts better with the 45pj.  The '12+ carbs seem to idle much better, but I am no jetting expert.  I believe there was a carb change for the 2012 model year.

[Wes Woodin]

On 9/5/2018 at 8:03 AM, gsa102 said:

Try a # 45 pilot jet first at that elevation.  IMO, The stock 40 is too lean until you get up to 2500+ feet.  I have always had idling issues with our 08, but it starts better with the 45pj.  The '12+ carbs seem to idle much better, but I am no jetting expert.  I believe there was a carb change for the 2012 model year.

yes there was a change in 2012. The way in which the accelerator pump actuator arm works is different. Pre 2012 the arm trailed the screw and is why the "O"ring modification existed. After 2012 the arm leads and pushes the screw so there is no need for the "O" ring modification. People still do the mod after 2012 not knowing, but it makes no difference.